What you should know about: Dengue (den-gee)

What is dengue?

Dengue is viral disease found primarily in urban and semi-urban areas of the tropics. It is transmitted by the Aedes mosquito, a domestic, day-biting mosquito that prefers to feed on humans. There are four types of dengue viruses, belonging to a family of viruses which include St Louis encephalitis virus, West Nile virus and yellow fever virus.

What are the symptoms of dengue? What does dengue cause?

Infection with dengue viruses produces an array of clinical illness ranging from a nonspecific viral set of symptoms to a severe and fatal hemorrhagic (bleeding) disease. Three to 14 days after infection, people suddenly experience high fever, severe frontal headache, pain behind the eyeball, and joint and muscle pain; many experience nausea and vomit. A rash may appear 3-5 days after onset of fever and can spread from the torso to the arms, legs, and face. Most people recover completely within two weeks.

Others develop severe bleeding problems. This complication is called dengue hemorrhagic fever (DHF), and can be fatal if untreated.

Who should be especially careful about dengue?

People living in and traveling to an endemic area (an area where dengue occurs regularly) during an epidemic are at increased risk of being infected with the virus. Persons who were previously infected with one or more types of dengue virus, who are very young or old, or who have a weak immune system are thought to be at greater risk for developing dengue hemorrhagic fever.

How common is dengue?

Dengue has become more common and widespread in the past 40 years. As of 2002, dengue fever is endemic in most tropical countries of the South Pacific, Asia, the Caribbean, the Americas, and Africa. Up to 100 million cases occur every year, with over 2 billion people at risk of contracting it.

Most cases of dengue fever in the U.S. have been linked to the patients' travel to endemic areas. The mosquito that transmits dengue fever is found in Texas and across the southeastern U.S., so there is a potential risk for dengue transmission. Sporadic outbreaks have occurred in the Gulf coastal area and in extreme south Texas.

How do people get dengue?

Dengue virus is transmitted to humans through the bites of infected female Aedes mosquitoes. Mosquitoes generally acquire the virus while feeding on the blood of an infected person. After virus incubation for 8-10 days, an infected mosquito is capable, while feeding, of transmitting the virus to humans for the rest of the mosquito's life.

Immunity to one of the four types of viruses does not protect a person from infection by another type.

How do I protect myself from dengue?

Because Aedes mosquitoes usually bite during the day, be sure to use precautions throughout the day, especially during early morning hours before daybreak and in the late afternoon before dark, when they are most active.

What do I do if I think I have dengue?

Advise your physician of any illness with fever occurring within 2-3 weeks after leaving a tropical area. If diagnosed with dengue, avoid pain relievers that contain aspirin; use those with acetaminophen instead. Rest and drink plenty of fluids.

How are dengue infections diagnosed?

Dengue is diagnosed by a blood test. The physician will have to rule out a variety of illness with similar course, including early stages of malaria, mild yellow fever, influenza, viral hepatitis, typhoid, Rift Valley fever, and leptospirosis.

How are dengue infections treated? How is dengue treated?

No vaccine is available for preventing or treating dengue infection. Treatment is supportive to ease symptoms. Dengue patients should be monitored for signs of DHF, especially hypotension (low blood pressure).

Should I worry about dengue when I travel out of the country?

Dengue occurs in most areas of tropical Asia, the Pacific Islands, the Caribbean Islands, Mexico, Central and South America, and Africa. The risk of dengue infection for the international traveler is small unless an epidemic is in progress during the time of travel. While traveling, in addition to the personal precautions indicated, spend as much time as possible in air-conditioned buildings, hotels, or other closed environments that mosquitoes cannot easily enter.